1. Field of the Invention
The present invention relates to a control apparatus for a hybrid vehicle which is mounted in a hybrid vehicle propulsion driven by jointly using an internal-combustion engine and a motor, and wherein the driving force from at least one of the internal-combustion engine and the motor is transmitted to the driving wheels.
This application is based on Japanese Patent Application No. 2003-192306, the contents of which are incorporated herein by reference.
2. Description of Related Art
Conventionally, for example, in a hybrid vehicle which comprises an internal-combustion engine and a motor as a power source and wherein the driving force from at least one of the internal-combustion engine and the motor is transmitted to the driving wheels for propulsion, a control apparatus for a hybrid vehicle has been well known which calculates the throttle opening for minimizing the fuel consumption of the internal-combustion engine with respect to the rotating speed of the input shaft of the transmission, and based on this throttle opening and the accelerator operation amount of a driver, allocates the torque required by the power plant (that is, the internal-combustion engine and the motor), into the engine torque required by the internal-combustion engine and the motor torque required by the motor (for example, refer to Japanese Unexamined Patent Application, First Publication No. Hei 9-163509).
Furthermore, in such a hybrid vehicle, there is known a control apparatus for a hybrid vehicle comprising an internal-combustion engine capable of being switched between an all cylinders operation which operates all cylinders and a partial cylinders deactivation operation which deactivates some of the cylinders (cylinders deactivation operation) as an internal-combustion engine low fuel consumption, which is aimed at improve the fuel consumption efficiency by performing the cylinders deactivation operation in the case where cylinders deactivation is possible such as during low speed travel.
Incidentally, in a control apparatus for a hybrid vehicle according to an example of the conventional technology, for example, there is a likelihood that, if the region capable the cylinders deactivation operation of the internal-combustion engine is enlarged by means of the assisting operation of motor, the assisting operation of the motor will be executed during medium load travel in urban areas with relatively higher travelling frequency compared to with high load travel on an uphill road, resulting in an increase in the frequency where the power storage device which transfers the electric energy with the motor comes into a state having a discharging trend. Consequently, for example at the time of acceleration of the vehicle, it becomes difficult to perform the desired assisting operation by the motor.
Furthermore, in the case where there is a likelihood of the power storage unit reaching an over discharging state, it is necessary to operate the motor as a generator by the output from the internal-combustion engine so as to charge the power storage unit, resulting in a problem that the fuel consumption efficiency is deteriorated, if the execution frequency of this power generation is increased.